Book of the All-Knowing is a manga concept by written and conceptualized by MythicalDX in late 2022 before being mentioned once again on January 5, 2024.

The series was one of many of Myth's manga concepts that was conceptualized in 2022. As of January 5, 2024, it has been mentioned again by Myth and has the potential to be a sequel to Purify that takes place in an alternate dimension in the save overall universe. A potential one-shot maybe in the works but all that's confirmed is there's a vague plot and protagonist.

MythicalDX, known as Myth, is the author and illustrator of Purify.

In 2018, Myth came up with the idea that would later become Purify and has been building on it since then. 

Full Article: MythicalDX

All though not published within the Mugen Trinity, It was first mentioned publicly in a drawing station on January 5, 2024.

Full Article: Mugen Trinity